erikk -- The airless paint sprayer pump sounds like an interesting idea for a vegoil pump, never thought of it. You mentioned "piston", if these are actually piston pumps,especially slow long stroke pistons, then they should work fine for thick oil, piston pumps are regularly used for thick fluid,even concrete. they can be drawn full slowly enough to give thick fluid time to move, and if they have a large diameter they can move lots of oil, I will do some research on these. I had seen a crew spraying polyurithane foam on the top of house roofs, this fluid is very thick and sticky, way worse than vegoil, there machine used compressed air to push/pull one air cylinded that was connected directly to the piston shaft of an even larger cylinder that the thick stuff was being pumped in and out of through large diamiter check valves, worked great.

On your unit - How is the pressure adjusting dial marked, does it have actual PSI markings or does it just indicat more/less pressure. Just wondering what pressures these pumps are able to create.

Spray nozzle -- I actually decided against an actual "spray" nozzle for just the reason you stated. A spray nozzle produces a cloud of very fine droplets, this would be fine to help release the water steam but unfortunatly this also results in a large amount of oil being blown out of the flash tank as a fine mist. I found that if I squirt a solid stream and impact it against a solid plate the water steam is still completely release but there is not as much oil turned into tiny droplets or vapor, this makes seperating the oil mist from the steam a bit easier just because there is less of the oil to remove. The paint sprayer nozzle might work well for the folks testing low pressure vacuum evaperative dewatering though.

The airless sprayer is one of the things I was going to try initially, still seems like a great idea.

The problem I see with thermostatically released solenoid valve is that a. water heater thermostats sometimes have a wide swing in between their opening and closing temperature. Perhaps that's only been reported by people whose thermostats are going bad- but apparently they sometimes cut off at a set temp but cut on again at a much lower temp. I guess it's also designed to prevent hysteresis (I really have to learn to spell that word)b you'll have to find a thermostat that goes higher than the boiling point of water, which I guess would make the concern above kinda irrelevant since you wouldn't be using a water heater-based one.

c. a PID control seems like a good thing there instead of a thermostat. They give much finer temperature control than mere thermostats can.

One of the things I want to test in the future is just how much heat is realy nescicary to dewater the oil thoroughly. Heat it the most power intensive part of this dewatering method, especially if you are using 12 volt DC on-vehicle power, if the amount of heat can be reduced it would make this a much more practical on-the-fly dewatering technique.

I actually see a good bit of vapor released from stone-cold oil when I first fire up the unit. It takes about 10 minutes for everything to get up to operating temperature so I have been returning the first 1/2 gallon of colder dewatered oil back to the wet oil supply barrel to insure it eventually got totally dewatered, I will test this cold oil for water content in the future.

The energy to boil off the water has to come from someplace, with 300 degree oil the energy is coming from the stored heat, the temperature of the 1/2 gallon of dryed oil inside the flash tank is much cooler than the 300 degrees inside the heater pipe. I have a thermomiter in the dry oil as it flows out of the flash tank, it changes from about 180 degrees f up to 230 degrees f depending on how much heat got used to flash off how much water. This outgoing oil is flowing out from about 3/4 of the way down from inside the tank so it has been inside the flash tank for a few minutes so these temps are probably a bit cooler than the freshly dewatered oil in the top of the tank. There is also energy stored in pressurising the oil, don't know how to relate this energy compared to heat energy exactly but there is a pressure change of 150 pounds across the oriface so the energy stored in this has to be going someplace, I am hoping it is also being used to help flash off the steam. If this is the case then this whole idea may change, instead of pressurizing the oil just enough to keep the water in it from boiling under added heat - what if it is pressurized to some considerably higher pressure without the heat, would there be enough energy in the pressure differance across the oriface to cause the water to flash off as steam ?? - This is beyond my current knowledge, will do more researching on this.

It is fairly easy to make higher pressures using 12 volts, at first look it seems easier to make pressure than to make the 1100 watts of heat that I am currently using. I am hoping that my current method of applying heat and pressure is overkill, would be nice if pressure alone would do the same thing.(Yes, I know, energy is energy, no matter what it's form - still seems like it will be easier to make pressure alone rather than heat and pressure, -- HHMMMM- the more I say it the less likely this pressure-only approach seems ?).

I am begining to suspect that a big part of why this squirt-hot-oil-through-a-small-oriface approach works better than simply heating a pot of oil has to do with forcibly breaking up the surface tension of the water microdroplets. Forcing these microdroplets through a tiny hole and bashing them into a steel plate has to do a much better job of breaking them up than simply floating them around in hot oil. I hope that by using this "bashing" concept the water can be released using less energy than pure math calculations concerning heat transfer energy seem to indicate. I will do testing using verious combinations of less heat and less/more pressures as time allows.

GM -- Thermostats -- This is one of the next improvements I hope to make. Ebay has someone that sells nice tiny temp controllers for around $50.00 including shipping. they always seem to be available. These are in a nice small 2 X 3 inch modern looking unit. This price also includes the temp probe. The control unit itself is powered with 6-24 volts ac/dc, the output of the unit is compatable with the 5-32 volt DC control input of almost all AC solid state relays to use as the power switch if using 110 volt AC heaters or would also control a high current FET transistor if you were using 12 volts DC to make the heat. this unit can be programmed to read and function in F or C, (I think).

These units are most likely based on a small microcontroller chip so should be pretty reliable, the price is cheaper than you could buy the individual parts for and it is packaged as a much nicer looking unit than anything you would make yourself.

I have no affiliation with these, wish I did, they look like a very small and versital unit. I have not yet bought or tested one of these but will be shortly, I am just relating info that is written on there sale page.

what about pulling a vaccume high enough to super heat the oil then close that valve. Then open a valve from a pressurized tank and fastly pressureize that tank. then Open a valve and let everything blast out a small orriface encouraging the water to steam out. orrr something to that effect. This would be a repeating cycle.

They are piston pumps. The length of the draw on the piston depends on the size of the pump its self. Some are more industrial size and made for acomidating larger volumes of paint or multiple paint lines running at one time. The one I have takes shorter faster piston pumps but is more than capable of moving wvo since it is much thinner than most paints I work with. I think the best thing about this pump is that is a "airless sprayer" no air is compressed through the line, that is how it mantains pressure. On my unit there isnt a psi dial but just a pressure dial. It seems like it would be easy enough to find the psi but when spraying paint so much depends on the size of the paint line, the gun and the size of the tip. After reading your thread a bit more I realized that you do not use a mist spray, makes sense.

Girl markGood point w the thermostat switches. I would be though that if you were to check in the Mcmaster catalog that you could find a pretty reliable industrial grade thermostat switch and probably a solinoid also. I am not sure what a PID is but it may make much more sense than a thermostaticly controlled system. Besides I really am not even slightly qualified to fork out any advice on this subject since the only hot oil I have sprayed is against my fender when I forgot to tighten my hose clamp. But I do think that an airless sprayer has potential, especially since it is made to pump solvent based products and the seals are nylon, propolyn, brass and other such materials besides rubber. If either of you are near the bay area in california and would like a sprayer I could get you a new one at a discount price (contractors discount) or at least help you find a good used one.Keep up the good threadErik

erikk -- I am definatly interested in this style of pump, I will do more research and keep an eye out for a cheap one to test with (one has to come through my local salvage yard eventually). The only concern is just how much pressure these can produce and what method they use to produce it or if it can be modified into what is needed. I would not expect the painting process to be using anywhere near a hundred pounds pressure but I sure could be wrong, absolutely no experiance with spray painting of any kind.

I actually bought a couple of check valves and some small air cylinders to do some testing of this style pump, got sidetracked someplace and never got past sucking some oil in/out by hand. Thanks for pointing out that the airless spray units use this approach.

PID -- I forget exactly what this stands for but it basically means the temp controller learns by doing - it watches how fast the temperature changes under different conditions and gets better at holding the temp close to setpoint by turning the heaters on before they normaly would be turned on by a simple thermostat. this is overkill for our needs but it is an easy thing to do with modern smart electronics. It's all in the programming.

jeepin -- HHMMM -- Don't think a vacuum will cause much heating, not even sure myself how much pressure it will take to induce heating, of it even works that way, I am hoping someone else will share there knowledge about this.

Tim I would say that an airless sprayer would create at least 150 lbs min and probably up to 300. It needs a great deal of pressure to force the thick paint through an orifice smaller than the point of a pin. I have accidentaly cut through the paint line before and the pressure shot the paint a good 50 feet or so. Check out graco, I think they have psi specs for the airless rigs the make. Thanks for all the usefull infoErik

Tim,I've been building one of these over the past few days per your design and I've had limited success. I'm trying to figure out a way to regulate the pressure right now and I was thinking of using an automotive pressure sender unit as the input to a PWM (pulse width modulation) dc motor control circuit. (I'll upload a schematic later if anyone's interested. )The problem is that I've found a few sender units at reasonable prices (and quite a few at not-so-reasonable prices), but not many specify the psi rating. Any suggestions? Do you know any vehicles with a stock gauge which reads 150 (or 180 or 200) psi?

Originally posted by erikk:If either of you are near the bay area in california and would like a sprayer I could get you a new one at a discount price (contractors discount) or at least help you find a good used one.Keep up the good threadErik

as a matter of fact, I am in Berkeley/Oakland, and I was thinking of working on my setup again soon with my 'intern' , Oakie from this forum.

Wanna come help when Oakie and I fire it up?

And, yes, I"d love to check out an airless sprayer for this purpose as it makes a lot more sense for some applications (like larger units, which is what I"m trying to work on)

I would love to work on it with you. I could possibly even bring my sprayer with me. I have a small one which is probably what you want. It needs the packings to be redone but I think that is all. Actually I would need to run some laquer thinner through it to get all the paint residue out. I would need some notice as I am pretty busy w work and my kid but it seems like it would be fun.Keep in touch.Erik

I just emailed the 'intern' (or employee? I'm a Vegoil Employer at this point...) to find out when is good for him. Where in the area are you? I have to take the whole rig to someone's back yard to make the mess, which will probably be a biodiesel homebrew site in Oakland near High St.

PerkHouse -- What pump are you using and what are the problems you are running in to ?

Pressure sensors -- I Have the same problem finding sensors, way too expensive for general use. Stewart-warner makes an engine oil sender that is rated to 150 pounds. I bought one and promptly ruined it by putting just slightly more than a 150 pounds on it. It is a resistive sensor that now indicates the max pressure all the time.

I intended to open it up and see if it was fixable but forgot all about it til now. It is about the size of an egg, this usually means that the pressure is being used to straighten out some sort of bent or coiled tube, the flexing is mechanically connected to an internal veriable resistor. I suspect I moved the resistor slider off the end of it's track, if so I should be able to repair it. Wonder where I put it.

Actually, I have been running my unit without any feedback in the pressure loop, no loop even. Since the oil flow does not change I use a veriable transformer (veriac) to adjust the AC voltage into the battery charger that is powering the shurflo 12 volt DC pump. I adjust the variac til the pump is creating 150 pounds pressure while oil is flowing through the oriface, pretty much forget about it after that. The pressure does not change more than a few pounds from the initial setting and that is caused by the heater pipe thermostat switching on/off. I am using a 50 ft drop cord to power my unit so when the heater turns on the 110 volt AC voltage drops just a bit so the pump slows down just a tiny bit, this drops the pressure a few pounds. When the heater turns off the pressure returns to the preset pressure. This has worked fine unatended for as long as 10 hours.

Due to reliability problems over long periods of time I recently replaced the pressure cutoff switch on the shurflo pump that I use on my filter setup. I replaced the on-pump pressure switch by plumbing a heavy-duty air compressor type pressure switch into the output side of the pump plumbing. Works but you need to power the pump with about 6 volts or it can make pressure faster than the switch can react to it. powering the pump with 12 volts the pressure would reach 160-170 pounds before the switch could shut the motor off, did not matter what you had the pressure switch adjusted to before hand. I think this problem is caused by the multi-diaphragm design of this pump, the diaphragms cause the pressure to pulse at a fast rate and the big switch just can not move fast enough to keep up with the fast pulses.

I intend to try to use the basic mechanical diaphragm and moving platform of one of these air compressor type switch units to make an analog proximity sensor type pressor sensor. I pulled out all the mechanical switching parts and am mounting a small magnet on the lever that is moved by the diaphragm. I will mount an analog hall-effect solid state sensor in a position to sense the magnet. Hopefully this will make a reasonably priced pressure sensor. The actual course pressure will be set the same way these switches normally work, by adjusting the preload on a spring that pushes against the diaphragm lever. once there is enough pressure to move the lever than the magnet will move close enough to the hall-effect sensor for it to start regulating the PW. That is the idea anyway.

I buy used salvaged air compressor switches from my local scrap yard for $5.00 each. they scrap out a couple of small home type air compressors a month, mostly due to rust causing pinhole leaks in the air tanks, the pressure switches are fine.

The furnace oil-pump that I am now testing eliminates all this external pressure control hassle because it has an adjustable pressure bypass valve type regulator already built in. Having an actual mechanical regulator provides a big safety improvement over my set-and-forget approach in case the oriface was to get clogged. The normal pressure range on these pumps is from 100-200 pounds, set by adjusting a screw, hard part is finding the correct specific pump. They are less than $100.00 new once I figure out what to order.

I have a couple of airless sprayers I picked up at garage sales. I'm not sure the actual pressure they make, but the hoses say 3000 PSI max. I've been told not to put my finger in front of the stream close to the orifice or it will inject paint into my skin (maybe just an old painter's tale, but I'm not brave enough to test that one out). The flow volume, though, is very low. One of my machines isn't working quite right and I was trying to get some crud out by running a bunch of hot water through. I stuck the intake in a full five gallon bucket, jammed the gun handle open full bore and went to eat lunch. I think it took about 45 minutes to go through all the water (granted, the pump isn't at its best right now). Given that we don't want to actually atomize the oil for this application, the orifice would be much bigger and therefore the pressure would be much lower than normal painting pressure.

Tim, I think your method, though very effective (qick and dirty, one might say), is overkill, in terms of energy use. If you're going to flash evaporate water out of the oil using electricity as the sole power source, I would think that the batch vacuum method that several others have set up would be far more energy efficient. With that method, you'd only be heating it to 140 or 150F and the rest of the energy usage would be running your refrigerator compressor. As much thought, energy, and time as you seem to put into your cool projects, I bet you could come up with a way to automate the process so that when one batch is done, it pumps the dewatered oil into a storage container and starts a new batch (I'm picturing some system using a series of 100 lb propane tanks, all full of oil. The vacuum pump does double duty by compressing a bunch of air in a tank, which can be used to push the dewatered oil into the storage tank and also to push new watery oil into the dewatering tank.)

A flame-heated flash evaporator would be far more efficient and cheaper and could run off low grade oil (tallows and such). However, it would probably be more difficult to control the temperature.

If your ultimate goal is to develop a system that you can use on your truck while driving, I would think that the vacuum system would be much better (unless you could use the exhaust as the heat source). The truck probably has a suitable vacuum pump in the form of the air conditioner, which is belt-driven and therefore does not require additional electricity from the alternator. Then the tank could be heated to near boiling temp with the coolant or with a heat exchanger from the exhaust. I wonder how much your fuel economy would change while processing a batch of oil.

I think I also have a way to create intense pressure inside a tank: fill a propane tank most of the way with your veg oil and the rest of the way with pure oxygen. Then make a spark inside the tank (maybe with a spark plug or something). I may be way off (and probably a little nuts) here, but I am sure something along this line could work safely if you set it up right. I don't think there would be an explosion, since oil isn't volatile at room temp. I think it would just burn until much or all of the oxygen was used up. If it did work, it should increase the pressure considerably and at a very low cost. If nothing else, it would be cool to test ways to combust vegetable oil in a sealed tank (at a safe distance, of course).

Shoot, why not just use an airles paint sprayer type pump in place of the IP? Then you would hardly have to filter it at all. I mean, a paint sprayer is made to pump fluid that's full of large and small particulate matter (paint pigments). I don't know how you would control the timing, but I bet it could be done.

Gosh, now I've got myself redesigning the engine components themselves. I know some of my ideas may not be practical, but I hope they at least inspire others to think of better ones that are more practical.

Two tank system on an '89 F250Working on an 81 Chevy ChevetteAttempting to resurrect a rusted out 85 Ford Tempo

Originally posted by Tim c cook:PerkHouse -- What pump are you using and what are the problems you are running in to ?

I'm using the HFT clearwater pump and although I haven't measured the pressure yet, I believe it's dangerously high. So, I used a PVC check valve off a 'T' to release the excess pressure which is released back to the source container, but I think the check valve is opening at around 50 psi or thereabouts. In its place, I put on a 150psi pressure relief valve from a hot water heater last night. Haven't fired it up yet to see how that goes.

Oh, and I didn't mean to imply that your design was flawed. Sorry if that came across. I only meant that since I don't have access to the same goodies, I've been improvising on a lot of different components which just add up to a mess.

For instance, the orifice: I haven't found a jet in the right ball park, so I had to make one. How? I drilled a 1/16" hole in the end of a pipe plug. (Waay too big, I know.) Then I placed a piece of thick, self-adhesive, stainless steel tape about the size of a nickel over the inside of the plug and the hole. I then used the bristle from a wire brush and some vise grips to poke a hole through the tape. It works ok, but I think the hole is actually too small. I'm guessing by the relative size to the 1/16" hole that it was around .001 (+/-) inch. Because of this, I was having a lot of plugging problems at first. That seems to be better now that I've added a hydraulic filter inline with the inlet to my pump.

Additionally, I took a very small nail with a very sharp point and enlarged the hole with as little force as I could muster yet still enough to expand the SS tape. Of course, I slipped and now I'd guess the hole is somewhere between 1/64" and 1/32". A bit larger than I'd hoped for, but I'm gonna give it a try. I can always cut a new piece of tape and try again.

So... now I should have an orifice that's about the right size (maybe a little big) and the pressure should be about 150psi. I'm putting a light dimmer on my heating element. (I've ordered some Watlow PIDs and might be willing to sell 1 or 2 at a discount in exchange for a couple of K-type thermocouples. Hey, anybody got a Shurflo they want to trade, even-up?)

quote:

Pressure sensors

Dakota Digital has one rated at 0-400psi for about $35 here, but I don't want to spend that much. Some new (electrical) sending units are as little as $6 or $8, but I don't know what the pressure rating is.

quote:

furnace oil-pump

Fuel-oil furnaces are still fairly popular in my area. I'll check out the landfill and salvage yard to see what I can find.

Ok, I got to test my mods today. I kept having clogging problems though. I think the junk was coming off my (used) heating element. Using a 3500W/220V element running on 115V, I was getting about 270F with the dimmer cranked all the way up.

Since I don't have a filter I can put right before the orifice, I removed the SS tape, so the orifice size became 1/16 (.0625) inch. I know that's huge, but my output temp was right at 220F and I got enormous amounts of steam. When I did the pan test, the "wet" oil had a bunch of pops and bubbles, the "dry" oil did have a few bubbles, but wasn't completely dry. I think that there were two factors: the orifice was too big & too much oil in the receiving container. I didn't have the oil overflowing into another container like Tim did, so as the level rose, the steam began to shoot down into the oil. It's highly likely that some of that steam recondensed in the oil. I'll try again tomorrow, but with a smaller batch.

On the positive side... I ran 8 gallons in about 90 minutes! Of course, since I have to run it through again, I guess I haven't really gained anything. Hopefully, if I just run about 3 gallons at a time, I won't have any bubbles.

Tim, have you done any more testing with minimum temperature? I was seeing vapor rise out of the barrel without any heat applied. Of course, it could have just been atomized oil, but I kinda doubt it.

PerkHouse -- Welcome to the flash club. Sounds about like some of my first testing.

Oriface -- I did my initial testing with the pilot light oriface from a salvage yard propane heated water heater ( propane, not natural gas, as there pilot oriface is way too big). These all seem to be a 13/1000 opening, worked fine for initial testing but you will have to use the original aluminum tube it has on the heater. I cut the tube about an inch long and put a standard brass compression fitting on the free end of the tube. at 150 pounds pressure it will flow just a bit less than 4 G/H

Oriface clogging -- Yep, it is literally a pain cleaning out a hot oriface. That is why I added the high-temp hydraulic filter just in front of the oriface. Before adding the filter I found that after cleaning the oriface 3-5 times, when starting the cold unit, you would finally get all the crud out and it would run for hours without clogging.

Pump -- If the HFT clear water pump is the blue 1/2 HP unit that a lot of folks are using for all sorts of uses. It is a centrifugal impeller pump and even if you block off the output completely it will only produce 35-40 pounds pressure max. This is not much pressure for this flash heating purpose and the water will boil at only a bit above the normal 212 degree point (look up "steam tables" on the net, it will tell you at what temp water boils when under different pressures), I am surprised that you got the water up to even 270 degrees, probably had a good bit of boiling going on onside the heater unit that increased the internal pressure somewhat, May not be a bad thing, never tried it, may dewater just fine. I still suspect that pushing the oil through a tiny oriface and bashing the tiny hot stream into something solid will force a mechanical release of water a lot better than simply heating the oil all at once in an big open container.

Heat -- a 220 volt 3500 watt heater on 110 volts will only make 1/4 that much heat - equals to 875 watts in this case. 270 deg f sounds about right for the somewhat larger oriface you have. My heater is 1100 watts and with 150 pounds pressure and my 18/000 oriface it runs almost all the time at the 5 G/H flowrate.

Have not done any low-temp testing yet. I will be dewatering in a couple of days so will do some quick-n-dirty testing then.

wvoalaska -- paint pumps and volume -- The volume depends on the size of the piston pump and the check valves used with it. One pump unit I saw filled the bed of a pickup truck and had 2 pistons 3 inches in diameter and about a 2 ft stroke. Pumped about a stroke every 2 seconds, made the truck dance pretty good.

Energy use -- It takes energy from someplace to convert the water to steam, you have to get it from someplace. It costs right at 1 1/2 cents of electricity for every 1 gallon of oil dewatered. This does not change no matter what flowrate the unit has, more gallons per hour costs more money per hour but you do not have to run it as long, all balances out.

Vacuum dewatering -- This sounds good but so far I have not seen anyone post that they actually have a unit that works completely yet. This approach is still in the early testing stages though. The "energy from someplace" is a problem with these vacuum units. You can only make 15 pounds of vacuum max and it still takes almost as much energy to flash off the steam, it just burst into vapor at a bit lower temp. One of the problems is that because the oil is not pressurized you can only heat it to 212 degrees before the water boils, the boiling eats up any further heat you put into it so you can not superheat the oil and get the flash off energy from the extra heat directly.

Mobile unit -- Yes, if the oil is preheated as hot as possible it will reduce the need for final electrical heating a lot. Problem is how to do it easily and controlably. definatly would use radiator water someplace in an actual unit. Once I understand the basics I will work on a portable unit.

Flame heat -- There is a link on the first page of this discussion to a 5 G/Minute oil fired unit. It definatly dryes oil a lot faster but has to be manually tweeked minute-by-minute to control the balance of temp and pressure. Reading about that unit is what started me down this path in the first place.

Oxygen and spark and oil -- I want to be in another state when you test this.

Airless paint sprayer -- because these use verious types of pistons or diaphragms as there pumps they look like they will work well with thick veg once tweeked, depends on just what you are trying to do. Have not had time to do much research on these yet.